Path Isolation Verification; Connections For Path Isolation Verification; Figure - Keithley 7174A Instruction Manual

4.6.4 Path isolation verification
The procedure for verifying path isolation is discussed be-
low. Should the card fail any of the tests, clean it using the
procedures outlined in paragraph 4.2.
Recommended equipment
• Model 707A Switching Matrix
• Model 617 Electrometer
• Model 7078-TRX-3 Triax Cable
• Unterminated 3-slot triaxial cable (cut connector off
7078-TRX-3)
• Banana plug (Keithley part #BG-10-2)
• #16-18AWG insulated stranded wire (6 in. length)
Test connections
Figure 4-4 shows the test connections for the path isolation
tests. One row being tested is to be connected to the Model
617 Electrometer input through a Model 6172 2-slot female
617 7174A
A
F
Equivalent Circuit

Figure 4-4

Connections for path isolation verification
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to 3-lug male triaxial adapter. The other row is to be con-
nected to the voltage source HI terminal using a specially
prepared 3-slot triax-to-banana plug cable, the construction
of which is shown in Figure 4-5. Note that both the inner
shield and the center conductor are to be connected to the
banana plug as shown.
COM and LO terminal of the electrometer voltage source
must be connected together as shown. Also, the ground link
between COM and chassis must be removed, and the Model
617 guard must be turned off for current measurements.
Procedure
6172
Adapter
Guard off
617 Electrometer
Row A
User-Prepared Triax Cable
Row B
Warning: Hazardous voltage from
the electrometer source
may be present on terminals.
WARNING
Hazardous voltage from the electrome-
ter voltage source will be used in the fol-
lowing steps. Take care not to contact
live circuits, which could cause personal
injury or death.
7078-TRX-3 Triax Cable
Ground Link
Removed
(See Figure 4-5)
Service Information
KEITHLEY 7174A
8 x 12 LOW
CURRENT MATRIX
SIGNAL
COLUMNS
200V PK 200V PK
GUARD
200V PK
ROWS
1
A
2
B
3
C
4
D
5
6
7
8
E
9
F
10
G
11
H
12
!
WARNING:
TIGHTEN MOUNTING SCREWS
TO ENSURE PROPER
CHASSIS GROUND
7174A Matrix Card
4-7